Bakers&#39;s Yeast Expressing Anti-Staling/Freshness Amylases

ABSTRACT

A recombinant yeast cell comprising a heterologous polynucleotide encoding an anti-staling/freshness amylase; in particular an anti-staling/freshness amylase selected from the group consisting of a maltogenic amylase (EC 3.2.1.133), a beta-amylase (EC 3.2.1.2), and a glucan 1,4-alpha-maltotetrahydrolase (EC 3.2.1.60).

REFERENCE TO A SEQUENCE LISTING

This application contains a Sequence Listing in computer readable form,which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a recombinant yeast cell expressing ananti-staling/freshness amylase, e.g., a maltogenic amylase for use inthe baking area.

BACKGROUND

Maltogenic amylases (E.C. 3.2.1.133) are able to hydrolyze amylose andamylopectin forming maltose as the main reaction product. A maltogenicamylase is described in, e.g., EP 120 693 and is commercially availableunder the trade name Novamyl® (product of Novozymes A/S).

Novamyl is widely used in the baking industry as ananti-staling/freshness agent due to its ability to reduce retrogradationof starch/amylopectin. Variants of Novamyl are disclosed in, e.g., WO99/43794.

Baker's yeast is normally used when producing breads, buns, etc.

It may be a substantial economic advantage if it is possible to make abaker's yeast that is capable of expressing anti-staling/freshnessenzymes.

Certain baking applications may also benefit from continuous release ofthe anti-staling/freshness enzymes as opposed to adding a fixed amountof enzyme granulate/enzyme liquid during the mixing stage.

SUMMARY

The present inventors have found that it is possible to produce arecombinant yeast cell comprising a heterologous polynucleotide encodinga functional anti-staling/freshness amylase that may be used in baking.

In one embodiment, we claim a recombinant yeast cell comprising aheterologous polynucleotide encoding an anti-staling/freshness amylaseselected from the group consisting of a maltogenic amylase (EC3.2.1.133), a beta-amylase (EC 3.2.1.2), and a glucan1,4-alpha-maltotetrahydrolase (EC 3.2.1.60).

In one embodiment, the heterologous polynucleotide encodes a maltogenicamylase having at least 70% sequence identity to amino acids 20-705 ofSEQ ID NO:1.

In one embodiment, the heterologous polynucleotide encodes a maltogenicamylase selected from the group consisting of amino acids 20-705 of SEQID NO:1, amino acids 20-705 of SEQ ID NO:2, and amino acids 20-705 ofSEQ ID NO:3.

In one embodiment, the heterologous polynucleotide encodes abeta-amylase polypeptide having at least 70% sequence identity to SEQ IDNO:4.

In one embodiment, the heterologous polynucleotide encodes a glucan1,4-alpha-maltotetrahydrolase having at least 70% sequence identity toSEQ ID NO:5.

In one embodiment, the heterologous polynucleotide comprises a codingsequence having at least 70% sequence identity to SEQ ID NO: 6, SEQ IDNO:7, or SEQ ID NO:8.

In one embodiment, the recombinant yeast cell is a Saccharomyces cell.

In one embodiment, the recombinant yeast cell is a Saccharomycescerevisiae cell.

In one embodiment, we claim a process for producing a dough, comprisingadding a recombinant yeast cell comprising a heterologous polynucleotideencoding an anti-staling/freshness amylase selected from the groupconsisting of a maltogenic amylase (EC 3.2.1.133), a beta-amylase (EC3.2.1.2), and a glucan 1,4-alpha-maltotetrahydrolase (EC 3.2.1.60) todough ingredients and making the dough.

In one embodiment, a baked or a steamed product is made from the dough.

In one embodiment, an enzyme selected from the group consisting ofamylase, glucanase, galactanase, mannanase, aminopeptidase,alpha-amylase, carboxypeptidase, catalase, chitinase, cutinase,cyclodextrin glycosyltransferase, deoxyribonuclease, esterase,alpha-galactosidase, beta-galactosidase, glucoamylase,alpha-glucosidase, beta-glucosidase, haloperoxidase, invertase, laccase,lipase, phospholipase, mannosidase, oxidase, pectinolytic enzymes,peptidoglutaminase, peroxidase, phytase, glucose oxidase,polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminaseand xylanase is added to the dough.

In one embodiment, one of the dough ingredients is flour.

In one embodiment, the flour is selected from the group consisting ofwheat, emmer, spelt, einkorn, barley, rye, oat, corn, sorghum, rice,millet, amaranth, quinoa, and cassava and any combinations thereof.

In one embodiment, we claim the use of the recombinant yeast cellaccording to present invention in dough making.

In one embodiment, the recombinant yeast cell is used as a Baker'syeast.

Definitions

Unless defined otherwise or clearly indicated by context, all technicaland scientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art.

Allelic variant: The term “allelic variant” means any of two or morealternative forms of a gene occupying the same chromosomal locus.Allelic variation arises naturally through mutation, and may result inpolymorphism within populations. Gene mutations can be silent (no changein the encoded polypeptide) or may encode polypeptides having alteredamino acid sequences. An allelic variant of a polypeptide is apolypeptide encoded by an allelic variant of a gene.

Coding sequence: The term “coding sequence” or “coding region” means apolynucleotide sequence, which specifies the amino acid sequence of apolypeptide. The boundaries of the coding sequence are generallydetermined by an open reading frame, which usually begins with the ATGstart codon or alternative start codons such as GTG and TTG and endswith a stop codon such as TAA, TAG, and TGA. The coding sequence may bea sequence of genomic DNA, cDNA, a synthetic polynucleotide, and/or arecombinant polynucleotide.

Control sequence: The term “control sequence” means a nucleic acidsequence necessary for polypeptide expression. Control sequences may benative or foreign to the polynucleotide encoding the polypeptide, andnative or foreign to each other. Such control sequences include, but arenot limited to, a leader sequence, polyadenylation sequence, propeptidesequence, promoter sequence, signal peptide sequence, and transcriptionterminator sequence. The control sequences may be provided with linkersfor the purpose of introducing specific restriction sites facilitatingligation of the control sequences with the coding region of thepolynucleotide encoding a polypeptide.

Disruption: The term “disruption” means that a coding region and/orcontrol sequence of a referenced gene is partially or entirely modified(such as by deletion, insertion, and/or substitution of one or morenucleotides) resulting in the absence (inactivation) or decrease inexpression, and/or the absence or decrease of enzyme activity of theencoded polypeptide. The effects of disruption can be measured usingtechniques known in the art such as detecting the absence or decrease ofenzyme activity using from cell-free extract measurements referencedherein; or by the absence or decrease of corresponding mRNA (e.g., atleast 25% decrease, at least 50% decrease, at least 60% decrease, atleast 70% decrease, at least 80% decrease, or at least 90% decrease);the absence or decrease in the amount of corresponding polypeptidehaving enzyme activity (e.g., at least 25% decrease, at least 50%decrease, at least 60% decrease, at least 70% decrease, at least 80%decrease, or at least 90% decrease); or the absence or decrease of thespecific activity of the corresponding polypeptide having enzymeactivity (e.g., at least 25% decrease, at least 50% decrease, at least60% decrease, at least 70% decrease, at least 80% decrease, or at least90% decrease). Disruptions of a particular gene of interest can begenerated by processes known in the art, e.g., by directed homologousrecombination (see Processes in Yeast Genetics (1997 edition), Adams,Gottschling, Kaiser, and Stems, Cold Spring Harbor Press (1998)).

Endogenous gene: The term “endogenous gene” means a gene that is nativeto the referenced host cell. “Endogenous gene expression” meansexpression of an endogenous gene.

Expression: The term “expression” includes any step involved in theproduction of the polypeptide including, but not limited to,transcription, post-transcriptional modification, translation,post-translational modification, and secretion. Expression can bemeasured, for example, to detect increased expression by techniquesknown in the art, such as measuring levels of mRNA and/or translatedpolypeptide.

Expression vector: The term “expression vector” means a linear orcircular DNA molecule that comprises a polynucleotide encoding apolypeptide and is operably linked to control sequences, wherein thecontrol sequences provide for expression of the polynucleotide encodingthe polypeptide. At a minimum, the expression vector comprises apromoter sequence, and transcriptional and translational stop signalsequences.

Heterologous polynucleotide: The term “heterologous polynucleotide” isdefined herein as a polynucleotide that is not native to the host cell;a native polynucleotide in which structural modifications have been madeto the coding region; a native polynucleotide whose expression isquantitatively altered as a result of a manipulation of the DNA byrecombinant DNA techniques, e.g., a different (foreign) promoter; or anative polynucleotide in a host cell having one or more extra copies ofthe polynucleotide to quantitatively alter expression. A “heterologousgene” is a gene comprising a heterologous polynucleotide.

Host cell: The term “host cell” means any cell type that is susceptibleto transformation, transfection, transduction, and the like with anucleic acid construct or expression vector. The term “host cell”encompasses any progeny of a parent cell that is not identical to theparent cell due to mutations that occur during replication. The term“recombinant cell” is defined herein as a non-naturally occurring hostcell comprising one or more (e.g., two, several) heterologouspolynucleotides.

Improved property: When the yeast comprising the anti-staling/freshnessamylase according to the invention, is incorporated into a flour and/ora dough in effective amounts, one or more properties are improvedcompared to a flour and/or a dough in which the yeast comprising theanti-staling/freshness amylase is not added.

The improved property may be determined by comparison of a dough and/ora baked product prepared with addition of the yeast comprising aheterologous polynucleotide encoding the anti-staling/freshness amylaseof the present invention, and a yeast without the heterologouspolynucleotide encoding the anti-staling/freshness amylase of thepresent invention in accordance with the methods described below.

Organoleptic qualities may be evaluated using procedures wellestablished in the baking industry, and may include, for example, theuse of a trained sensory panel.

Improved extensibility: The term “improved extensibility of the dough”is defined herein as the property of dough that can be subjected toincreased stretching without rupture.

Increased strength: The term “increased strength of the dough” isdefined herein as the property of dough that has generally more elasticproperties and/or requires more work input to mould and shape.

Increased elasticity: The term “increased elasticity of the dough” isdefined herein as the property of dough which has a higher tendency toregain its original shape after being subjected to a certain physicalstrain.

Increased stability of the dough: The term “increased stability of thedough” is defined herein as the property of dough that is lesssusceptible to mechanical abuse thus better maintaining its shape andvolume and is evaluated by the ratio of height:width of a cross sectionof a loaf after normal and/or extended proof.

Reduced stickiness of the dough: The term “reduced stickiness of thedough” is defined herein as the property of a dough that has lesstendency to adhere to surfaces, e.g., in the dough production machinery,and is either evaluated empirically by the skilled test baker ormeasured by use of a texture analyzer (e.g., TAXT2) as known in the art.

Improved machine ability: The term “improved machine ability of thedough” is defined herein as the property of a dough that is generallyless sticky and/or more firm and/or more elastic.

Increased volume of the dough/the baked product: The term “increasedvolume of the dough/baked product” is measured as the volume of a doughor the volume of a given loaf of bread. The volume may, e.g., bedetermined by the rape seed displacement method, or by a skilled baker,or by using, e.g., a Volscan profiler 600.

Improved crumb structure of the baked product: The term “improved crumbstructure of the baked product” is defined herein as the property of abaked product regarding crumb uniformity, cell wall thickness, and thesize of the individual gas cells pores on the slice of bread.

The crumb structure of the baked product is usually evaluated visuallyby the baker or by digital image analysis as known in the art (e.g.,C-cell, Calibre Control International Ltd, Appleton, Warrington, UK).

Improved anti-staling/freshness of the baked product: The term “improvedanti-staling/freshness of the baked product” is the opposite of“firmness” and is defined herein as the property of a baked product thatis more easily compressed and is evaluated either empirically by theskilled test baker or measured by use of a texture analyzer (e.g., TAXT2or TA.XT Plus from Stable Micro Systems Ltd, Surrey, UK) as known in theart.

Nucleic acid construct: The term “nucleic acid construct” means apolynucleotide comprises one or more (e.g., two, several) controlsequences. The polynucleotide may be single-stranded or double-stranded,and may be isolated from a naturally occurring gene, modified to containsegments of nucleic acids in a manner that would not otherwise exist innature, or synthetic.

Operably linked: The term “operably linked” means a configuration inwhich a control sequence is placed at an appropriate position relativeto the coding sequence of a polynucleotide such that the controlsequence directs expression of the coding sequence.

Sequence Identity: The relatedness between two amino acid sequences orbetween two nucleotide sequences is described by the parameter “sequenceidentity”.

For purposes described herein, the degree of sequence identity betweentwo amino acid sequences is determined using the Needleman-Wunschalgorithm (Needleman and Wunsch, J. Mol. Biol. 1970, 48, 443-453) asimplemented in the Needle program of the EMBOSS package (EMBOSS: TheEuropean Molecular Biology Open Software Suite, Rice et al., TrendsGenet 2000, 16, 276-277), preferably version 3.0.0 or later. Theoptional parameters used are gap open penalty of 10, gap extensionpenalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62)substitution matrix. The output of Needle labeled “longest identity”(obtained using the −nobrief option) is used as the percent identity andis calculated as follows:

(Identical Residues×100)/(Length of the Referenced Sequence−Total Numberof Gaps in Alignment)

For purposes described herein, the degree of sequence identity betweentwo deoxyribonucleotide sequences is determined using theNeedleman-Wunsch algorithm (Needleman and Wunsch, 1970) as implementedin the Needle program of the EMBOSS package (EMBOSS: The EuropeanMolecular Biology Open Software Suite, Rice et al., 2000), preferablyversion 3.0.0 or later. The optional parameters used are gap openpenalty of 10, gap extension penalty of 0.5, and the EDNAFULL (EMBOSSversion of NCBI NUC4.4) substitution matrix. The output of Needlelabeled “longest identity” (obtained using the −nobrief option) is usedas the percent identity and is calculated as follows:

(Identical Deoxyribonucleotides×100)/(Length of ReferencedSequence−Total Number of Gaps in Alignment)

Reference to “about” a value or parameter herein includes embodimentsthat are directed to that value or parameter per se. For example,description referring to “about X” includes the embodiment “X”. Whenused in combination with measured values, “about” includes a range thatencompasses at least the uncertainty associated with the process ofmeasuring the particular value, and can include a range of plus or minustwo standard deviations around the stated value.

Likewise, reference to a gene or polypeptide that is “derived from”another gene or polypeptide X, includes the gene or polypeptide X.

As used herein and in the appended claims, the singular forms “a,” “or,”and “the” include plural referents unless the context clearly dictatesotherwise.

It is understood that the embodiments described herein include“consisting” and/or “consisting essentially of” embodiments. As usedherein, except where the context requires otherwise due to expresslanguage or necessary implication, the word “comprise” or variationssuch as “comprises” or “comprising” is used in an inclusive sense, i.e.,to specify the presence of the stated features but not to preclude thepresence or addition of further features in various embodiments.

DETAILED DESCRIPTION Anti-Staling/Freshness Amylases

The Applicant has found that it is possible to express a functionalanti-staling/freshness amylase in a yeast cell, such as a Saccharomycescerevisiae yeast cell, and use this recombinant yeast cell in baking.

Accordingly, in one aspect a recombinant yeast cell comprising aheterologous polynucleotide encoding an anti-staling/freshness amylaseis claimed, wherein anti-staling/freshness enzyme is selected from thegroup consisting of a maltogenic amylase (EC 3.2.1.133), a beta-amylase(EC 3.2.1.2), and a glucan 1,4-alpha-maltotetrahydrolase (EC 3.2.1.60).

In one embodiment, the maltogenic amylase comprises or consists of theamino acids 20-705 of SEQ ID NO: 1.

In another embodiment, the maltogenic amylase is a fragment of SEQ IDNO: 1 (e.g., wherein the fragment has maltogenic amylase activity). Inone embodiment, the number of amino acid residues in the fragment is atleast 75%, e.g., at least 80%, 85%, 90%, or 95% of the number of aminoacid residues in the maltogenic amylase of SEQ ID NO: 1.

The maltogenic amylase may be a variant of the maltogenic amylase of SEQID NO: 1. In one embodiment, the maltogenic amylase has at least 70%,e.g., at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%,98%, 99%, or 100% sequence identity to amino acids 20-705 of SEQ ID NO:1.

In one embodiment, the maltogenic amylase comprises or consists of theamino acids 20-705 of SEQ ID NO: 2 or comprises or consists of the aminoacids 20-705 of SEQ ID NO:3.

In one embodiment, the maltogenic amylase sequence differs by no morethan ten amino acids, e.g., by no more than five amino acids, by no morethan four amino acids, by no more than three amino acids, by no morethan two amino acids, or by one amino acid from amino acid sequence ofmaltogenic amylase of SEQ ID NO: 1. In one embodiment, the maltogenicamylase has an amino acid substitution, deletion, and/or insertion ofone or more (e.g., two, several) of amino acid sequence of the of SEQ IDNO: 1. In some embodiments, the total number of amino acidsubstitutions, deletions and/or insertions is not more than 10, e.g.,not more than 9, 8, 7, 6, 5, 4, 3, 2, or 1.

In one embodiment, the beta-amylase comprises or consists of the aminoacid sequence of SEQ ID NO: 4. In another embodiment, the beta-amylaseis a fragment of SEQ ID NO: 4 (e.g., wherein the fragment hasbeta-amylase activity). In one embodiment, the number of amino acidresidues in the fragment is at least 75%, e.g., at least 80%, 85%, 90%,or 95% of the number of amino acid residues in the beta-amylase of SEQID NO: 4.

The beta-amylase may be a variant of the beta-amylase of SEQ ID NO: 4.In one embodiment, the beta-amylase has at least 70%, e.g., at least75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%sequence identity to the beta-amylase of SEQ ID NO: 4.

In one embodiment, the beta-amylase sequence differs by no more than tenamino acids, e.g., by no more than five amino acids, by no more thanfour amino acids, by no more than three amino acids, by no more than twoamino acids, or by one amino acid from amino acid sequence ofbeta-amylase of SEQ ID NO: 4. In one embodiment, the beta-amylase has anamino acid substitution, deletion, and/or insertion of one or more(e.g., two, several) of amino acid sequence of the of SEQ ID NO: 4. Insome embodiments, the total number of amino acid substitutions,deletions and/or insertions is not more than 10, e.g., not more than 9,8, 7, 6, 5, 4, 3, 2, or 1.

In one embodiment, the glucan 1,4-alpha-maltotetrahydrolase comprises orconsists of the amino acid sequence of SEQ ID NO: 5. In anotherembodiment, the glucan 1,4-alpha-maltotetrahydrolase is a fragment ofSEQ ID NO: 5 (e.g., wherein the fragment has maltotetraohydrolaseactivity). In one embodiment, the number of amino acid residues in thefragment is at least 75%, e.g., at least 80%, 85%, 90%, or 95% of thenumber of amino acid residues in the maltogenic amylase of SEQ ID NO: 5.

The glucan 1,4-alpha-maltotetrahydrolase may be a variant of the glucan1,4-alpha-maltotetrahydrolase of SEQ ID NO: 5. In one embodiment, theglucan 1,4-alpha-maltotetrahydrolase has at least 70%, e.g., at least75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%sequence identity to the glucan 1,4-alpha-maltotetrahydrolase of SEQ IDNO: 5.

In one embodiment, the glucan 1,4-alpha-maltotetrahydrolase sequencediffers by no more than ten amino acids, e.g., by no more than fiveamino acids, by no more than four amino acids, by no more than threeamino acids, by no more than two amino acids, or by one amino acid fromamino acid sequence of glucan 1,4-alpha-maltotetrahydrolase of SEQ IDNO: 5. In one embodiment, the glucan 1,4-alpha-maltotetrahydrolase hasan amino acid substitution, deletion, and/or insertion of one or more(e.g., two, several) of amino acid sequence of the of SEQ ID NO: 5. Insome embodiments, the total number of amino acid substitutions,deletions and/or insertions is not more than 10, e.g., not more than 9,8, 7, 6, 5, 4, 3, 2, or 1.

The amino acid changes are generally of a minor nature, that isconservative amino acid substitutions or insertions that do notsignificantly affect the folding and/or activity of the protein; smalldeletions, typically of one to about 30 amino acids; smallamino-terminal or carboxyl-terminal extensions, such as anamino-terminal methionine residue; a small linker peptide of up to about20-25 residues; or a small extension that facilitates purification bychanging net charge or another function, such as a poly-histidine tract,an antigenic epitope or a binding domain.

Examples of conservative substitutions are within the group of basicamino acids (arginine, lysine and histidine), acidic amino acids(glutamic acid and aspartic acid), polar amino acids (glutamine andasparagine), hydrophobic amino acids (leucine, isoleucine and valine),aromatic amino acids (phenylalanine, tryptophan and tyrosine), and smallamino acids (glycine, alanine, serine, threonine and methionine). Aminoacid substitutions that do not generally alter specific activity areknown in the art and are described, for example, by H. Neurath and R. L.Hill, 1979, In, The Proteins, Academic Press, New York. The mostcommonly occurring exchanges are Ala/Ser, Val/Ile, Asp/Glu, Thr/Ser,Ala/Gly, Ala/Thr, Ser/Asn, Ala/Val, Ser/Gly, Tyr/Phe, Ala/Pro, Lys/Arg,Asp/Asn, Leu/Ile, Leu/Val, Ala/Glu, and Asp/Gly.

Alternatively, the amino acid changes are of such a nature that thephysico-chemical properties of the polypeptides are altered. Forexample, amino acid changes may improve the thermal stability of theanti-staling/freshness amylase, alter the substrate specificity, changethe pH optimum, and the like.

Essential amino acids can be identified according to procedures known inthe art, such as site-directed mutagenesis or alanine-scanningmutagenesis (Cunningham and Wells, 1989, Science 244: 1081-1085). In thelatter technique, single alanine mutations are introduced at everyresidue in the molecule, and the resultant mutant molecules are testedfor activity to identify amino acid residues that are critical to theactivity of the molecule. See also, Hilton et al., 1996, J. Biol. Chem.271: 4699-4708. The active site or other biological interaction can alsobe determined by physical analysis of structure, as determined by suchtechniques as nuclear magnetic resonance, crystallography, electrondiffraction, or photoaffinity labeling, in conjunction with mutation ofputative contact site amino acids. See, for example, de Vos et al.,1992, Science 255: 306-312; Smith et al., 1992, J. Mol. Biol. 224:899-904; Wlodaver et al., 1992, FEBS Lett. 309: 59-64.

Guidance on the structure-activity relationship ofanti-staling/freshness amylases described herein can be inferred fromnumerous crystal structures analyzed and known in the art. Additionalguidance on the structure-activity relationship ofanti-staling/freshness amylases can be determined using multiplesequence alignment (MSA) techniques well-known in the art. Suchalignments aid the skilled artisan to determine potentially relevantdomains (e.g., binding domains or catalytic domains), as well as whichamino acid residues are conserved and not conserved among the differentanti-staling/freshness amylase sequences. It is appreciated in the artthat changing an amino acid that is conserved at a particular positionbetween disclosed polypeptides will more likely result in a change inbiological activity (Bowie et al., 1990, Science 247: 1306-1310:“Residues that are directly involved in protein functions such asbinding or catalysis will certainly be among the most conserved”). Incontrast, substituting an amino acid that is not highly conserved amongthe polypeptides will not likely or significantly alter the biologicalactivity.

Single or multiple amino acid substitutions, deletions, and/orinsertions can be made and tested using known processes of mutagenesis,recombination, and/or shuffling, followed by a relevant screeningprocedure, such as those disclosed by Reidhaar-Olson and Sauer, 1988,Science 241: 53-57; Bowie and Sauer, 1989, Proc. Natl. Acad. Sci. USA86: 2152-2156; WO 95/17413; or WO 95/22625. Other processes that can beused include error-prone PCR, phage display (e.g., Lowman et al., 1991,Biochemistry 30: 10832-10837; U.S. Pat. No. 5,223,409; WO 92/06204), andregion-directed mutagenesis (Derbyshire et al., 1986, Gene 46: 145; Neret al., 1988, DNA 7: 127).

Mutagenesis/shuffling processes can be combined with high-throughput,automated screening processes to detect activity of cloned, mutagenizedpolypeptides expressed by host cells (Ness et al., 1999, NatureBiotechnology 17: 893-896). Mutagenized DNA molecules that encode activeanti-staling/freshness amylases can be recovered from the host cells andrapidly sequenced using standard processes in the art. These processesallow the rapid determination of the importance of individual amino acidresidues in a polypeptide.

Polynucleotides Encoding Anti-Staling/Freshness Amylases

The heterologous polynucleotide encoding the anti-staling/freshnessamylase may comprise a coding sequence having at least 70%, e.g., atleast 75%, at least 80%, at least 85%, at least 90%, at least 95%, atleast 96%, at least 97%, at least 98%, at least 99%, or 100% sequenceidentity to nucleotides of SEQ ID NO: 6, SEQ ID NO: 7, or SEQ ID NO: 8.

In one embodiment, the heterologous polynucleotide encoding theanti-staling/freshness amylase comprises or consists of the codingsequence of SEQ ID NO: 21. In another embodiment, the heterologouspolynucleotide encoding the anti-staling/freshness amylase comprises asubsequence of the coding sequence of SEQ ID NO: 6, SEQ ID NO: 7, or SEQID NO: 8. In another embodiment, the number of nucleotides residues inthe coding subsequence is at least 75%, e.g., at least 80%, 85%, 90%, or95% of the number of the referenced coding sequence.

The referenced coding sequence of any related aspect or embodimentdescribed herein can be the native coding sequence or a degeneratesequence, such as a codon-optimized coding sequence designed for aparticular host cell.

The polynucleotide coding sequence of SEQ ID NO: 6, SEQ ID NO: 7, or SEQID NO: 8, or a subsequence thereof, may be used to design nucleic acidprobes to identify and clone DNA encoding an anti-staling/freshnessamylase from strains of different genera or species according toprocesses well known in the art.

In particular, such probes can be used for hybridization with thegenomic DNA or cDNA of a cell of interest, following standard Southernblotting procedures, in order to identify and isolate the correspondinggene therein. Such probes can be considerably shorter than the entiresequence, but should be at least 15, e.g., at least 25, at least 35, orat least 70 nucleotides in length. Preferably, the nucleic acid probe isat least 100 nucleotides in length, e.g., at least 200 nucleotides, atleast 300 nucleotides, at least 400 nucleotides, at least 500nucleotides, at least 600 nucleotides, at least 700 nucleotides, atleast 800 nucleotides, or at least 900 nucleotides in length. Both DNAand RNA probes can be used. The probes are typically labeled fordetecting the corresponding gene (for example, with ³²P, ³H, ³⁵S,biotin, or avidin).

A genomic DNA or cDNA library prepared from such other strains may bescreened for DNA that hybridizes with the probes described above andencodes a parent. Genomic or other DNA from such other strains may beseparated by agarose or polyacrylamide gel electrophoresis, or otherseparation techniques. DNA from the libraries or the separated DNA maybe transferred to and immobilized on nitrocellulose or other suitablecarrier material. In order to identify a clone or DNA that hybridizeswith SEQ ID NO: 6, SEQ ID NO: 7, or SEQ ID NO: 8, or a subsequencethereof, the carrier material is used in a Southern blot.

In one embodiment, the nucleic acid probe is a polynucleotide comprisingSEQ ID NO: 6, SEQ ID NO: 7, or SEQ ID NO: 8; or a subsequence thereof.In another embodiment, the nucleic acid probe is a polynucleotide thatencodes the anti-staling/freshness amylase of SEQ ID NO: 6, SEQ ID NO:7, or SEQ ID NO: 8; or a fragment thereof.

For purposes of the probes described above, hybridization indicates thatthe polynucleotide hybridizes to a labeled nucleic acid probe, or thefull-length complementary strand thereof, or a subsequence of theforegoing; under very low to very high stringency conditions. Moleculesto which the nucleic acid probe hybridizes under these conditions can bedetected using, for example, X-ray film.

In one embodiment, the anti-staling/freshness amylase is encoded by apolynucleotide that hybridizes under at least low stringency conditions,e.g., medium stringency conditions, medium-high stringency conditions,high stringency conditions, or very high stringency conditions with thefull-length complementary strand of SEQ ID NO: 6, SEQ ID NO: 7, or SEQID NO: 8. (Sambrook et al., 1989, Molecular Cloning, A LaboratoryManual, 2d edition, Cold Spring Harbor, N.Y.).

The anti-staling/freshness amylase may be obtained from microorganismsof any suitable genus, including those readily available within theUniProtKB database (www.uniprot.org).

The anti-staling/freshness amylase may be a bacterialanti-staling/freshness amylase. For example, the anti-staling/freshnessamylase may be a Gram-positive bacterial polypeptide such as a Bacillus,Clostridium, Enterococcus, Geobacillus, Lactobacillus, Lactococcus,Oceanobacillus, Staphylococcus, Streptococcus, or Streptomycesanti-staling/freshness amylase, or a Gram-negative bacterial polypeptidesuch as a Campylobacter, E. coli, Flavobacterium, Fusobacterium,Helicobacter, Ilyobacter, Neisseria, Pseudomonas, Salmonella, orUreaplasma anti-staling/freshness amylase.

The anti-staling/freshness amylase may be a fungalanti-staling/freshness amylase. For example, the anti-staling/freshnessamylase may be a yeast anti-staling/freshness amylase such as a Candida,Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces, Yarrowia orIssatchenkia anti-staling/freshness amylase; or a filamentous fungalanti-staling/freshness amylase such as an Acremonium, Agaricus,Alternaria, Aspergillus, Aureobasidium, Botryosphaeria, Ceriporiopsis,Chaetomidium, Chrysosporium, Claviceps, Cochliobolus, Coprinopsis,Coptotermes, Corynascus, Cryphonectria, Cryptococcus, Diplodia, Exidia,Filibasidium, Fusarium, Gibberella, Holomastigotoides, Humicola, Irpex,Lentinula, Leptospaeria, Magnaporthe, Melanocarpus, Meripilus, Mucor,Myceliophthora, Neocallimastix, Neurospora, Paecilomyces, Penicillium,Phanerochaete, Piromyces, Poitrasia, Pseudoplectania,Pseudotrichonympha, Rhizomucor, Schizophyllum, Scytalidium, Talaromyces,Thermoascus, Thielavia, Tolypocladium, Trichoderma, Trichophaea,Verticillium, Volvariella, or Xylaria anti-staling/freshness amylase.

It will be understood that for the afore mentioned species, theinvention encompasses both the perfect and imperfect states, and othertaxonomic equivalents, e.g., anamorphs, regardless of the species nameby which they are known. Those skilled in the art will readily recognizethe identity of appropriate equivalents.

Strains of these species are readily accessible to the public in anumber of culture collections, such as the American Type CultureCollection (ATCC), Deutsche Sammlung von Mikroorganismen andZellkulturen GmbH (DSMZ), Centraalbureau Voor Schimmelcultures (CBS),and Agricultural Research Service Patent Culture Collection, NorthernRegional Research Center (NRRL).

The anti-staling/freshness amylase may also be identified and obtainedfrom other sources including microorganisms isolated from nature (e.g.,soil, composts, water, silage, etc.) or DNA samples obtained directlyfrom natural materials (e.g., soil, composts, water, silage, etc.) usingthe above-mentioned probes. Techniques for isolating microorganisms andDNA directly from natural habitats are well known in the art. Thepolynucleotide encoding an anti-staling/freshness amylase may then bederived by similarly screening a genomic or cDNA library of anothermicroorganism or mixed DNA sample.

Once a polynucleotide encoding an anti-staling/freshness amylase hasbeen detected with a suitable probe as described herein, the sequencemay be isolated or cloned by utilizing techniques that are known tothose of ordinary skill in the art. Techniques used to isolate or clonepolynucleotides encoding anti-staling/freshness amylase includeisolation from genomic DNA, preparation from cDNA, or a combinationthereof. The cloning of the polynucleotides from such genomic DNA can beeffected, e.g., by using the well-known polymerase chain reaction (PCR)or antibody screening of expression libraries to detect cloned DNAfragments with shares structural features. See, e.g., Innis et al.,1990, PCR: A Guide to Processes and Application, Academic Press, NewYork. Other nucleic acid amplification procedures such as ligase chainreaction (LCR), ligated activated transcription (LAT) and nucleotidesequence-based amplification (NASBA) may be used.

The anti-staling/freshness amylase may be a fused polypeptide orcleavable fusion polypeptide in which another polypeptide is fused atthe N-terminus or the C-terminus of the anti-staling/freshness amylase.

Hosts Cells and Recombinant Processes

The yeast host cells for preparing the recombinant cells describedherein can be from any suitable yeast host, such as a Saccharomycescell. Preferably, the yeast cell is a Saccharomyces cerevisiae cell.Suitable cells can, for example, be derived from commercially availablestrains such as polyploid or aneuploid industrial strains, including butnot limited to those from Baker's Best Yeast, Baker's Compressed Yeast,Baker's Dry Yeast etc. (commercially available as, e.g., Fleischmann'sYeast).

Other useful yeast strains are available from biological depositoriessuch as the American Type Culture Collection (ATCC) or the DeutscheSammlung von Mikroorganismen and Zellkulturen GmbH (DSMZ).

The recombinant cells described herein may utilize expression vectorscomprising the coding sequence of one or more (e.g., two, several)heterologous genes linked to one or more control sequences that directexpression in a suitable cell under conditions compatible with thecontrol sequence(s). Such expression vectors may be used in any of thecells and processes described herein. The polynucleotides describedherein may be manipulated in a variety of ways to provide for expressionof a desired polypeptide. Manipulation of the polynucleotide prior toits insertion into a vector may be desirable or necessary depending onthe expression vector. The techniques for modifying polynucleotidesutilizing recombinant DNA processes are well known in the art.

A construct or vector (or multiple constructs or vectors) comprising theone or more (e.g., two, several) heterologous genes may be introducedinto a cell so that the construct or vector is maintained as achromosomal integrant or as a self-replicating extra-chromosomal vectoras described earlier.

The various nucleotide and control sequences may be joined together toproduce a recombinant expression vector that may include one or more(e.g., two, several) convenient restriction sites to allow for insertionor substitution of the polynucleotide at such sites. Alternatively, thepolynucleotide(s) may be expressed by inserting the polynucleotide(s) ora nucleic acid construct comprising the sequence into an appropriatevector for expression. In creating the expression vector, the codingsequence is located in the vector so that the coding sequence isoperably linked with the appropriate control sequences for expression.

The recombinant expression vector may be any vector (e.g., a plasmid orvirus) that can be conveniently subjected to recombinant DNA proceduresand can bring about expression of the polynucleotide. The choice of thevector will typically depend on the compatibility of the vector with thehost cell into which the vector is to be introduced. The vector may be alinear or closed circular plasmid.

The vector may be an autonomously replicating vector, i.e., a vectorthat exists as an extrachromosomal entity, the replication of which isindependent of chromosomal replication, e.g., a plasmid, anextrachromosomal element, a mini-chromosome, or an artificialchromosome. The vector may contain any means for assuringself-replication. Alternatively, the vector may be one that, whenintroduced into the host cell, is integrated into the genome andreplicated together with the chromosome(s) into which it has beenintegrated. Furthermore, a single vector or plasmid or two or morevectors or plasmids that together contain the total DNA to be introducedinto the genome of the cell, or a transposon, may be used.

The expression vector may contain any suitable promoter sequence that isrecognized by a cell for expression of a gene described herein. Thepromoter sequence contains transcriptional control sequences thatmediate the expression of the polypeptide. The promoter may be anypolynucleotide that shows transcriptional activity in the cell of choiceincluding mutant, truncated, and hybrid promoters, and may be obtainedfrom genes encoding extracellular or intracellular polypeptides eitherhomologous or heterologous to the cell.

Each heterologous polynucleotide described herein may be operably linkedto a promoter that is foreign to the polynucleotide. For example, in oneembodiment, the heterologous polynucleotide encoding theanti-staling/freshness amylase is operably linked to a promoter foreignto the polynucleotide. The promoters may be identical to or share a highdegree of sequence identity (e.g., at least about 80%, at least about85%, at least about 90%, at least about 95%, or at least about 99%) witha selected native promoter.

Examples of suitable promoters for directing the transcription of thenucleic acid constructs in a yeast cells, include, but are not limitedto, the promoters obtained from the genes for enolase, (e.g., S.cerevisiae enolase or I. orientalis enolase (ENO1)), galactokinase(e.g., S. cerevisiae galactokinase or I. orientalis galactokinase(GAL1)), alcohol dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase(e.g., S. cerevisiae alcohol dehydrogenase/glyceraldehyde-3-phosphatedehydrogenase or I. orientalis alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH1,ADH2/GAP)), triose phosphate isomerase (e.g., S. cerevisiae triosephosphate isomerase or I. orientalis triose phosphate isomerase (TPI)),metallothionein (e.g., S. cerevisiae metallothionein or I. orientalismetallothionein (CUP1)), 3-phosphoglycerate kinase (e.g., S. cerevisiae3-phosphoglycerate kinase or I. orientalis 3-phosphoglycerate kinase(PGK)), PDC1, xylose reductase (XR), xylitol dehydrogenase (XDH),L-(+)-lactate-cytochrome c oxidoreductase (CYB2), translation elongationfactor-1 (TEF1), translation elongation factor-2 (TEF2),glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and orotidine5′-phosphate decarboxylase (URA3) genes. Other useful promoters foryeast host cells are described by Romanos et al., 1992, Yeast 8:423-488.

The control sequence may also be a suitable transcription terminatorsequence, which is recognized by a host cell to terminate transcription.The terminator sequence is operably linked to the 3′-terminus of thepolynucleotide encoding the polypeptide. Any terminator that isfunctional in the yeast cell of choice may be used. The terminator maybe identical to or share a high degree of sequence identity (e.g., atleast about 80%, at least about 85%, at least about 90%, at least about95%, or at least about 99%) with the selected native terminator.

Suitable terminators for yeast host cells may be obtained from the genesfor enolase (e.g., S. cerevisiae or I. orientalis enolase cytochrome C(e.g., S. cerevisiae or I. orientalis cytochrome (CYC1)),glyceraldehyde-3-phosphate dehydrogenase (e.g., S. cerevisiae or I.orientalis glyceraldehyde-3-phosphate dehydrogenase (gpd)), PDC1, XR,XDH, transaldolase (TAL), transketolase (TKL), ribose 5-phosphateketol-isomerase (RKI), CYB2, and the galactose family of genes(especially the GAL10 terminator).

The control sequence may also be an mRNA stabilizer region downstream ofa promoter and upstream of the coding sequence of a gene which increasesexpression of the gene.

Examples of suitable mRNA stabilizer regions are obtained from aBacillus thuringiensis cryIIIA gene (WO 94/25612) and a Bacillussubtilis SP82 gene (Hue et al., 1995, Journal of Bacteriology 177:3465-3471).

The control sequence may also be a suitable leader sequence, whentranscribed is a nontranslated region of an mRNA that is important fortranslation by the host cell. The leader sequence is operably linked tothe 5′-terminus of the polynucleotide encoding the polypeptide. Anyleader sequence that is functional in the yeast cell of choice may beused.

Suitable leaders for yeast host cells are obtained from the genes forenolase (e.g., S. cerevisiae or I. orientalis enolase (ENO-1)),3-phosphoglycerate kinase (e.g., S. cerevisiae or I. orientalis3-phosphoglycerate kinase), alpha-factor (e.g., S. cerevisiae or I.orientalis alpha-factor), and alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (e.g., S.cerevisiae or I. orientalis alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP)).

The control sequence may also be a polyadenylation sequence; a sequenceoperably linked to the 3′-terminus of the polynucleotide and, whentranscribed, is recognized by the host cell as a signal to addpolyadenosine residues to transcribed mRNA. Any polyadenylation sequencethat is functional in the host cell of choice may be used. Usefulpolyadenylation sequences for yeast cells are described by Guo andSherman, 1995, Mol. Cellular Biol. 15: 5983-5990.

It may also be desirable to add regulatory sequences that allow theregulation of the expression of the polypeptide relative to the growthof the host cell. Examples of regulatory systems are those that causethe expression of the gene to be turned on or off in response to achemical or physical stimulus, including the presence of a regulatorycompound. Regulatory systems in prokaryotic systems include the lac,tac, and trp operator systems. In yeast, the ADH2 system or GAL1 systemmay be used.

The vectors may contain one or more (e.g., two, several) selectablemarkers that permit easy selection of transformed, transfected,transduced, or the like cells. A selectable marker is a gene the productof which provides for biocide or viral resistance, resistance to heavymetals, prototrophy to auxotrophs, and the like. Suitable markers foryeast host cells include, but are not limited to, ADE2, HIS3, LEU2,LYS2, MET3, TRP1, and URA3.

The vectors may contain one or more (e.g., two, several) elements thatpermit integration of the vector into the host cell's genome orautonomous replication of the vector in the cell independent of thegenome.

For integration into the host cell genome, the vector may rely on thepolynucleotide's sequence encoding the polypeptide or any other elementof the vector for integration into the genome by homologous ornon-homologous recombination. Alternatively, the vector may containadditional polynucleotides for directing integration by homologousrecombination into the genome of the host cell at a precise location(s)in the chromosome(s). To increase the likelihood of integration at aprecise location, the integrational elements should contain a sufficientnumber of nucleic acids, such as 100 to 10,000 base pairs, 400 to 10,000base pairs, and 800 to 10,000 base pairs, which have a high degree ofsequence identity to the corresponding target sequence to enhance theprobability of homologous recombination. The integrational elements maybe any sequence that is homologous with the target sequence in thegenome of the host cell. Furthermore, the integrational elements may benon-encoding or encoding polynucleotides. On the other hand, the vectormay be integrated into the genome of the host cell by non-homologousrecombination. Potential integration loci include those described in theart (e.g., See US2012/0135481).

For autonomous replication, the vector may further comprise an origin ofreplication enabling the vector to replicate autonomously in the yeastcell. The origin of replication may be any plasmid replicator mediatingautonomous replication that functions in a cell. The term “origin ofreplication” or “plasmid replicator” means a polynucleotide that enablesa plasmid or vector to replicate in vivo. Examples of origins ofreplication for use in a yeast host cell are the 2 micron origin ofreplication, ARS1, ARS4, the combination of ARS1 and CEN3, and thecombination of ARS4 and CEN6.

More than one copy of a polynucleotide described herein may be insertedinto a host cell to increase production of a polypeptide. An increase inthe copy number of the polynucleotide can be obtained by integrating atleast one additional copy of the sequence into the yeast cell genome orby including an amplifiable selectable marker gene with thepolynucleotide where cells containing amplified copies of the selectablemarker gene, and thereby additional copies of the polynucleotide, can beselected for by cultivating the cells in the presence of the appropriateselectable agent.

The procedures used to ligate the elements described above to constructthe recombinant expression vectors described herein are well known toone skilled in the art.

Dough

In one aspect, the invention discloses a method for preparing dough or abaked product prepared from the dough which method comprisesincorporating into the dough a recombinant yeast cell comprising aheterologous polynucleotide encoding an anti-staling/freshness amylaseaccording to the invention.

In another aspect, the invention provides dough comprising flour, water,and an effective amount of a recombinant yeast cell comprising aheterologous polynucleotide encoding an anti-staling/freshness amylaseaccording to the present invention.

The present invention also relates to methods for preparing a dough or abaked product comprising incorporating into the dough an effectiveamount of a recombinant yeast cell comprising a heterologouspolynucleotide encoding an anti-staling/freshness amylase which improvesone or more properties of the dough or the baked product obtained fromthe dough relative to a dough or a baked product in which therecombinant yeast cell comprising a heterologous polynucleotide encodingan anti-staling/freshness amylase is not incorporated.

The phrase “incorporating into the dough” is defined herein as addingthe recombinant yeast cell comprising a heterologous polynucleotideencoding an anti-staling/freshness amylase according to the invention tothe dough, to any ingredient from which the dough is to be made, and/orto any mixture of dough ingredients from which the dough is to be made.

The recombinant yeast cell comprising a heterologous polynucleotideencoding an anti-staling/freshness amylase is added to the ingredientsof dough that may be kneaded and baked to make the baked product usingmethods well known in the art.

The term “effective amount” is defined herein as an amount of therecombinant yeast cell comprising a heterologous polynucleotide encodingan anti-staling/freshness amylase according to the invention that issufficient for providing a measurable effect on at least one property ofinterest of the dough and/or baked product.

The term “dough” is defined herein as a mixture of flour and otheringredients firm enough to knead or roll. In the context of the presentinvention, batters are encompassed in the term “dough”.

The dough of the invention may comprise flour derived from any cerealgrain or other sources, including wheat, emmer, spelt, einkorn, barley,rye, oat, corn, sorghum, rice, millet, amaranth, quinoa, and cassava,and any combinations thereof.

The dough may also comprise other conventional dough ingredients, e.g.,proteins, such as milk powder, gluten, and soy; eggs (either whole eggs,egg yolks, or egg whites); an oxidant such as ascorbic acid, potassiumbromate, potassium iodate, azodicarbonamide (ADA) or ammoniumpersulfate; an amino acid such as L-cysteine; a sugar; a salt such assodium chloride, calcium acetate, sodium sulfate, or calcium sulfate,and/or an emulsifier.

The dough may comprise fat (triglyceride) such as granulated fat orshortening.

The dough of the invention may be fresh, frozen or par-baked(pre-baked).

The dough of the invention is leavened dough or dough to be subjected toleavening.

Emulsifiers

For some applications, an emulsifier is not needed, but for otherapplications an emulsifier may be needed.

A suitable emulsifier for use in the present invention is preferably anemulsifier selected from the group consisting of diacetyl tartaric acidesters of monoglycerides (DATEM), sodium stearoyl lactylate (SSL),calcium stearoyl lactylate (CSL), ethoxylated mono- and diglycerides(EMG), distilled monoglycerides (DMG), polysorbates (PS), andsuccinylated monoglycerides (SMG).

Additional Enzymes

Optionally, one or more additional enzymes such as aminopeptidase,amylase, alpha-amylase, maltogenic amylase, beta-amylase,carboxypeptidase, catalase, chitinase, cutinase, cyclodextringlycosyltransferase, deoxyribonuclease, esterase, galactanase,glucanase, alpha-galactosidase, beta-galactosidase, glucoamylase,alpha-glucosidase, beta-glucosidase, haloperoxidase, invertase, laccase,mannanase, mannosidase, oxidase, pectinolytic enzymes,peptidoglutaminase, peroxidase, phospholipase, phytase,polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase,and/or xylanase may be used together with the recombinant yeast cellcomprising a heterologous polynucleotide encoding ananti-staling/freshness amylase according to the present invention.

The glucoamylase for use in the present invention include glucoamylaseshaving a sequence identity of at least 50%, at least 60%, at least 65%,at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99% tothe amino acid sequence of the A. niger G1 or G2 glucoamylase (Boel etal. (1984), EMBO J. 3 (5), p. 1097-1102), the A. awamori glucoamylasedisclosed in WO 84/02921, or the A. oryzae glucoamylase (Agric. Biol.Chem. (1991), 55 (4), p. 941-949).

The added amylase may be added to the dough on top of the amylaseproduced by the recombinant yeast cell according to the presentinvention. The amylase may be fungal or bacterial, e.g., a maltogenicamylase, a beta-amylase, or a fungal alpha-amylase, e.g., from A.oryzae.

Suitable commercial maltogenic alpha-amylases include NOVAMYL, OPTICAKE50 BG, and OPTICAKE 3D (available from Novozymes NS). Suitablecommercial fungal alpha-amylase compositions include, e.g., BAKEZYME P300 (available from DSM) and FUNGAMYL 2500 SG, FUNGAMYL 4000 BG,FUNGAMYL 800 L, FUNGAMYL ULTRA BG and FUNGAMYL ULTRA SG (available fromNovozymes NS).

The amylase may also be an amylase (glucan1,4-alpha-maltotetrahydrolase) from, e.g., Pseudomonas, such as any ofthe amylases disclosed in WO1999/050399, WO2004/111217, orWO2005/003339; e.g., G4™/G+™ available from DuPont.

The glucose oxidase may be a fungal glucose oxidase, in particular anAspergillus niger glucose oxidase (such as GLUZYME®, available fromNovozymes NS).

The hemicellulase may be a pentosanase, e.g., a xylanase which may be ofmicrobial origin, e.g., derived from a bacterium or fungus, such as astrain of Aspergillus, in particular of A. aculeatus, A. niger, A.awamori, or A. tubigensis, from a strain of Trichoderma, e.g., T.reesei, or from a strain of Humicola, e.g., H. insolens.

Suitable commercially available xylanase preparations for use in thepresent invention include PANZEA BG, PENTOPAN MONO BG and PENTOPAN 500BG (available from Novozymes NS), GRINDAMYL POWERBAKE (available fromDuPont), and BAKEZYME BXP 5000 and BAKEZYME BXP 5001 (available fromDSM).

The protease may be from Bacillus, e.g., B. amyloliquefaciens or fromThermus aquaticus.

Baked Product

The dough of the invention may be used for any kind of steamed or bakedproduct prepared from dough, either of a white, light or dark type.

Examples are bread (in particular white, whole-meal or rye bread),typically in the form of loaves or rolls, bread, pita bread, tortillas,cakes, pancakes, biscuits, wafers, cookies, pie crusts, steamed bread,pizza and the like.

The invention described and claimed herein is not to be limited in scopeby the specific aspects herein disclosed, since these aspects areintended as illustrations of several aspects of the invention. Anyequivalent aspects are intended to be within the scope of thisinvention. Indeed, various modifications of the invention in addition tothose shown and described herein will become apparent to those skilledin the art from the foregoing description.

The following examples are offered to illustrate certain aspects of thepresent invention, but not in any way intended to limit the scope of theinvention as claimed.

EXAMPLES Example 1

Construction of Plasmid Vectors Expressing an Anti-Staling/FreshnessAmylase

Expression cassettes for the desired anti-staling/freshness amylaseswere targeted to the X-2 integration sites as described in Mikkelsen etal. (Metabolic Engineering v14 (2012) pp 104-111).

Two plasmids employing a split-marker approach were used for eachintegration event, each containing an expression cassette andapproximately two-thirds of a dominant selection marker. The left-handplasmid contained 5′ flanking DNA homologous to the X-2 integrationsite, the S. cerevisiae TEF2 promoter driving expression of the gene ofinterest codon-optimized for expression in S. cerevisiae, the S.cerevisiae ADH3 terminator, a loxP site, and the 5′ two-thirds of adominant selection marker under control of the Ashbya gossypii TEF1promoter. The right-hand plasmid contains the 3′ two-thirds of thedominant selection marker with the Ashbya gossypii TEF1 terminator, aloxP site, an expression cassette in the reverse orientation relative tothe dominant selection marker composed of the S. cerevisiae HXT7promoter driving expression of the gene of interest codon-optimized forexpression in S. cerevisiae with the S. cerevisiae PMA1 terminator, and3′ flanking DNA homologous to the X-2 integration site. The plasmidsused for the strain construction are shown in Table 1 below:

TABLE 1 Plasmid name left- or right-hand marker SEQ ID pMHCT379 leftkanamycin 1 pMHCT380 left kanamycin 2 pMHCT381 left kanamycin 3 pMHCT384right kanamycin 1 pMHCT385 right kanamycin 2 pMHCT386 right kanamycin 3pMHCT387 left nourseothricin 1 pMHCT388 left nourseothricin 2 pMHCT389left nourseothricin 3 pMHCT390 right nourseothricin 1 pMHCT391 rightnourseothricin 2 pMHCT392 right nourseothricin 3

Example 2

Construction of Recombinant Yeast Cells Expressing anAnti-Staling/Freshness Amylase

Expression cassettes for the desired anti-staling/freshness amylase weretargeted to the X-2 integration site of S. cerevisiae strain in acommercially available Fleischmann yeast using lithium acetatetransformation (Gietz D, St. Jean A, Woods R, Schiestl R (1991) Improvedmethod for high efficiency transformation of intact yeast cells. NucleicAcids Research 20 (6) 1425).

Linearized DNAs corresponding to left- and right-hand expressioncassettes with the kanamycin marker and linearized DNAs corresponding toleft- and right-hand expression cassettes with the nourseothricin markerwere simultaneously transformed into Fleischmann yeast and transformantsresistant to both kanamycin and nourseothricin were selected, followedby PCR screening to confirm the desired integration events.

The antibiotic markers present in the above created strains are flankedby loxP sites. These intermediate strains were transformed with plasmidpFYD80 that includes a gene encoding the CRE recombinase, asite-specific enzyme that facilitates recombination between neighboringloxP sites (Güldener U, Heinisch J, Köhler G J, Voss D, Hegemann J H(2002) A second set of loxP marker cassettes for Cre-mediated multiplegene knockouts in budding yeast. Nucl Acids Res 30: e23).

Plasmid pFYD80 is maintained as a non-integrative, free replicatingmolecule. This approach enables the specific excision of both selectivemarkers. The intermediate strains were transformed with plasmid pFYD80,and transformants were selected on plates containing zeocin. Zeocinresistance is encoded in pFYD80. Subsequently, screening fortransformants that have lost nourseothricin and kanamycin resistance wasperformed. Sensitive strains were grown in YPD liquid until loss ofpFYD80 plasmid was obtained.

Following this protocol, strain “Baker's yeast expressing SEQ ID NO:1”was selected and shown to be sensitive to zeocin, kanamycin, andnourseothricin. Strain “Baker's yeast expressing SEQ ID NO:1” is derivedfrom S. cerevisiae strain Fleischmann yeast and expresses SEQ ID NO:1from the X-2 integration site, one copy under control of the TEF2promoter and the other copy under control of the HXT7 promoter. SinceFleischmann yeast is a tetraploid, two of the four X-2 chromosomal locicontain this tandem expression cassette, while the remaining two copiesof X-2 remain wild-type.

Following this protocol, strain “Baker's yeast expressing SEQ ID NO:2”was selected and shown to be sensitive to zeocin, kanamycin, andnourseothricin. Strain “Baker's yeast expressing SEQ ID NO:2” is derivedfrom S. cerevisiae strain Fleischmann yeast and expresses SEQ ID NO:2from the X-2 integration site, one copy under control of the TEF2promoter and the other copy under control of the HXT7 promoter. SinceFleischmann yeast is a tetraploid, two of the four X-2 chromosomal locicontain this tandem expression cassette, while the remaining two copiesof X-2 remain wild-type.

Following this protocol, strain “Baker's yeast expressing SEQ ID NO: 3”was selected and shown to be sensitive to zeocin, kanamycin, andnourseothricin. Strain “Baker's yeast expressing SEQ ID NO: 3” isderived from S. cerevisiae strain Fleischmann yeast and expresses SEQ IDNO:3 from the X-2 integration site, one copy under control of the TEF2promoter and the other copy under control of the HXT7 promoter. SinceFleischmann yeast is a tetraploid, two of the four X-2 chromosomal locicontain this tandem expression cassette, while the remaining two copiesof X-2 remain wild-type.

Example 3

Baking Test with Baker's Yeast Expressing an Anti-Staling/FreshnessAmylase

The ability of three yeast samples expressing anti-staling/freshnessamylases to provide leavening and freshness was tested in a bakingexperiment employing bread samples based on 16 g dough pieces.

The baking experiment included the following four yeast samples:

1) Baker's yeast (Control-Fleischmann yeast)

2) Baker's yeast expressing SEQ ID NO:2 (made according to Example 2)

3) Baker's yeast expressing SEQ ID NO: 3 (made according to Example 2)

4) Baker's yeast expressing SEQ ID NO:1 (made according to Example 2)

Additionally, a benchmark of Novamyl 10000 BG (50 ppm, based on flour)was made.

The leavening ability of the yeast samples was verified by comparingvolume of bread prepared with yeast with volume of bread preparedwithout yeast.

Mini-bread was prepared from the following ingredients:

Standard wheat flour 100.0 g (Kolibri, Meneba BV, Rotterdam, Holland)Water 58.5 g Standard baker's yeast 5.0 g Salt 1.5 g Sugar 1.5 gAscorbic acid 4 mg

Water content of the different yeast preparations was not identicalwhich is why yeast was dosed on dry matter.

The dry matter of the yeast preparations was determined by placingapproximately 500 mg yeast preparation on tarred aluminium trays in anoven (106° C.) over night. Dry matter of commercial baker's yeastcontained approximately 31% dry matter, and all samples were dosed toequal 5 g yeast with this dry matter content.

Yeast expressing anti-staling/freshness amylase had lower dry mattercompared to commercial baker's yeast which is why more yeast was addedto ensure equal dry matter addition. The additional water added from theyeast preparations expressing freshness amylases were compensated byadding less water to the recipe.

Dough was prepared by mixing the ingredients for 4 minutes using a Model325 gram Swanson pin mixer (National Manufacturing, TMG. Co. Lincoln,Nebr., US).

After mixing, dough was divided in 9 dough pieces of 16 g. Each doughpiece was placed in closed pans (cylindrical pan, diameter 52 mm andheight 30 mm). Dough was proofed for 55 min at 36° C. and 80% relativehumidity and subsequently baked for 12 min at 210° C. After baking, themini-bread samples were cooled and packed with nitrogen gas in sealedplastic bags.

On day 1, 3, and 8 after baking, the top of the mini-bread was removedwith a knife and a cutting-box leaving 2 cm bread sample was obtained.

Crumb hardness was evaluated using a TA.XT plus Texture Analyzer (StableMicro Systems, Surrey, UK) equipped with a spherical probe (25.4 mmdiameter).

The bread sample was compressed 40% of the original height at a speed of1.7 mm/s. Crumb hardness in grams at 25% compression was used tocharacterize the bread crumb hardness.

The leavening ability of the yeast samples were verified because allyeast-containing samples filled out the closed pan (63.7 mL) as opposedto dough prepared without yeast which had a volume after baking ofapproximately 15 mL.

Table 2 below shows crumb hardness as function of storage time of thethree yeast preparations expressing anti-staling/freshness amylases. Thetable also includes hardness development for bread prepared with yeastnot expressing anti-staling/freshness amylases (Control), and breadprepared with yeast not expressing anti-staling/freshness amylases butadded commercial anti-staling/freshness amylase (Control+50 ppm Novamyl10000BG).

TABLE 2 Crumb hardness (g) after 1, 3, and 8 days of storage Day 1 Day 3Day 8 Control 190 532 693 Control + Novamyl 108 283 346 10000BG (50 ppmbased on flour) Yeast expressing 146 361 598 SEQ ID NO: 2 Yeastexpressing 146 435 693 SEQ ID NO: 3 Yeast expressing 146 486 770 SEQ IDNO: 1

It can be seen from Table 2 that the lowest increase in crumb hardnessover time was observed for bread added commercial enzyme granulate (bestanti-staling/freshness effect). Yeast expressing SEQ ID NO:2 caused ananti-staling/freshness effect in between the Control and the “Controladded Novamyl 10000BG”.

Yeast expressing SEQ ID NO: 3 and SEQ ID NO:1 caused lower crumbhardness on day 3, while no differences appeared to exist between thesetwo samples and the Control on Day 8.

Example 4

Baker's Yeast Expressing an Anti-Staling/Freshness Amylase in a Spongeand Dough Baking Test

The yeast strains used in Example 3 were used in a sponge and doughbaking trial:

-   -   Baker's yeast (Control-Fleischmann yeast)    -   Baker's yeast expressing SEQ ID NO: 2    -   Baker's yeast expressing SEQ ID NO: 3    -   Baker's yeast expressing SEQ ID NO:1    -   Additionally, a benchmark of Novamyl 10000 BG (50 ppm, based on        flour) was made.

The baking trial was performed in 15 g scale in lidded pans.

The ingredients in the sponge (see Table 3) were placed in a 200 g pinmixer (National MFG Co, Lincoln, Nebr., USA) and mixed into a sponge for3 minutes at 90 rounds per minute. The sponge was placed in a largeplastic container and proofed in a proofing cabinet for 3 h at 27° C.75% rH.

The sponge was again placed in the 200 g pin mixer together with theingredients of the dough (see Table 3) and mixed for 3 min at 90 roundsper minute into a dough. The dough was divided into nine 15 gram doughpieces that were rounded by hand into a roll and placed in a cylindricalpan with lid.

The lidded pan was placed on a continuous conveyor belt where the doughfirst was proofed for 63 min at 36° C. and 80% rH and baked for 10.5 minat 210° C.

After baking, the bread was removed from the pans and allowed to cooldown for 10 min at room temperature after which they were placed in asealed plastic bag and stored at room temperature until analyzed forcrumb firmness.

Crumb firmness was evaluated using a TA.XT plus Texture Analyzer (StableMicro Systems, Surrey, UK) equipped with a spherical probe (25.4 mmdiameter).

The bread sample was compressed 40% of the original height at a speed of1.7 mm/s. Crumb firmness in grams at 25% compression was used tocharacterize the bread crumb firmness.

TABLE 3 Recipe Ingredients Amount Sponge Flour (Wigwam, US white flour)70 g Water 40.6 g Soybean oil 3 g Yeast dry matter (See 4) 2.15 g DoughFlour (Wigwam, US white flour) 30 g Water 20.4 g Sugar 5 g Salt 2 gCalcium Propionate 0.35 g Ascorbic acid 60 ppm

Results

TABLE 4 Effect of different yeast strains on change in Firmness (g)measured with texture analyzer Name Day 1 Day 3 Day 7 1 Control(Standard yeast - 93 398 506 Fleischmann) 2 Standard yeast + Novamyl 96269 358 10000 BG 3 Yeast expressing 79 241 355 SEQ ID NO: 2 4 Yeastexpressing 86 303 404 SEQ ID NO: 3 5 Yeast expressing 85 270 453 SEQ IDNO: 1

It can be seen from Table 4 that yeast expressing anti-staling/freshnessenzymes were all better than the control; and the yeast expressing SEQID NO:2 was even better than adding 50 ppm Novamyl 10000 BG.

Example 5

Construction of Recombinant Yeast Cells Expressing Increased Amounts ofAnti-Staling/Freshness Amylase

To increase the amount of anti-staling/freshness amylase secreted fromthe yeast, the expression cassettes as described in Example 1 werere-transformed into the yeast strains constructed in Example 2. To doso, the expression cassettes for the desired anti-staling/freshnessamylase were targeted to the X-2 integration site of strains “Baker'syeast expressing SEQ ID NO: 1”, “Baker's yeast expressing SEQ ID NO: 2,”and “Baker's yeast expressing SEQ ID NO: 3” using lithium acetatetransformation (Gietz D, St. Jean A, Woods R, Schiestl R (1991) Improvedmethod for high efficiency transformation of intact yeast cells. NucleicAcids Research 20 (6) 1425). Linearized DNAs corresponding to left- andright-hand expression cassettes with the kanamycin marker and linearizedDNAs corresponding to left- and right-hand expression cassettes with thenourseothricin marker were simultaneously transformed into the strainsmade in Example 2 with the matching poly-nucleotide. Transformantsresistant to both kanamycin and nourseothricin were selected, followedby PCR screening. Since initial PCR screening for loss of the wild-typeX-2 locus showed that all transformants still contained a wild-typelocus, as second PCR primer set was used. These second PCR primersflanked the drug markers (nourseothricin and kanamycin). PCR resultsthat showed both a larger band (the size expected when the drug markerswere present) and a smaller band (the expected size after marker removalas described in Example 2) indicated that these isolates contained threechromosomes modified at the X-2 locus: one chromosome containing themarker-less expression cassette as made in Example 2, plus twoadditional modified chromosomes, one with the expression cassettecontaining the nourseothricin marker and one with the expressioncassette containing the kanamycin marker. This lead to “Baker's yeastexpressing SEQ ID NO: 1, three cassettes+markers”, “Baker's yeastexpressing SEQ ID NO: 2, three cassettes+markers,” and “Baker's yeastexpressing SEQ ID NO: 3, three cassettes+markers.”

Following this protocol, strain “Baker's yeast expressing SEQ ID NO:3,three cassettes+markers” was selected and shown to be sensitive tozeocin, kanamycin, and nourseothricin. Strain “Baker's yeast expressingSEQ ID NO:3, three cassettes+markers” is derived from S. cerevisiaestrain Fleischmann yeast and expresses SEQ ID NO:3 from the X-2integration site, one copy under control of the TEF2 promoter and theother copy under control of the HXT7 promoter. Since Fleischmann yeastis a tetraploid, three of the four X-2 chromosomal loci contain thistandem expression cassette (two of which also contain drug markers),while the remaining one copy of X-2 remains wild-type.

The markers were removed from strains “Baker's yeast expressing SEQ IDNO: 1, three cassettes+markers” and “Baker's yeast expressing SEQ ID NO:2, three cassettes+markers” using the pFYD80 plasmid as described inExample 2.

Following this protocol, strain “Baker's yeast expressing SEQ ID NO:1,three cassettes” was selected and shown to be sensitive to zeocin,kanamycin, and nourseothricin. Strain “Baker's yeast expressing SEQ IDNO:1” is derived from S. cerevisiae strain Fleischmann yeast andexpresses SEQ ID NO:1 from the X-2 integration site, one copy undercontrol of the TEF2 promoter and the other copy under control of theHXT7 promoter. Since Fleischmann yeast is a tetraploid, three of thefour X-2 chromosomal loci contain this tandem expression cassette, whilethe remaining one copy of X-2 remains wild-type.

Following this protocol, strain “Baker's yeast expressing SEQ ID NO:2,three cassettes” was selected and shown to be sensitive to zeocin,kanamycin, and nourseothricin. Strain “Baker's yeast expressing SEQ IDNO:1” is derived from S. cerevisiae strain Fleischmann yeast andexpresses SEQ ID NO:1 from the X-2 integration site, one copy undercontrol of the TEF2 promoter and the other copy under control of theHXT7 promoter. Since Fleischmann yeast is a tetraploid, three of thefour X-2 chromosomal loci contain this tandem expression cassette, whilethe remaining one copy of X-2 remains wild-type.

Example 6

Baker's Yeast Expressing an Increased Level of Anti-Staling/FreshnessAmylase in a Sponge and Dough Baking Test

Yeast strains constructed as described in Example 5 were used in asponge and dough baking trial:

-   -   Baker's yeast (Control-Fleischmann yeast)    -   Baker's yeast expressing SEQ ID NO: 2, three cassettes    -   Baker's yeast expressing SEQ ID NO: 1, three cassettes    -   Baker's yeast expressing SEQ ID NO: 3, three cassettes+markers    -   Additionally, a benchmark of Novamyl 10000 BG (50 ppm, based on        flour) was made.

The baking procedure was the same as described in Example 4 using therecipe described in Table 5.

TABLE 5 Recipe Ingredients Amount Sponge Flour (Wigwam, US white flour)70 g Water 40.6 g Soybean oil 3 g Yeast dry matter (See 4) 2.15 g DoughFlour (Wigwam, US white flour) 30 g Water 20.4 g Sugar 5 g Salt 2 gCalcium Propionate 0.35 g Ascorbic acid 60 ppm

After baking, the bread was removed from the pans and allowed to cooldown for 10 min at room temperature after which they were placed in asealed plastic bag and stored at room temperature until analyzed forcrumb firmness.

Crumb firmness was evaluated using a TA.XT plus Texture Analyzer (StableMicro Systems, Surrey, UK) equipped with a spherical probe (25.4 mmdiameter).

The bread sample was compressed 40% of the original height at a speed of1.7 mm/s. Crumb firmness in grams at 25% compression was used tocharacterize the bread crumb firmness.

Results

TABLE 6 Effect of different yeast strains on change in Firmness (g)measured with texture analyzer Name Day 1 Day 3 Day 7 1 Control(Standard yeast - 117 293 428 Fleischmann) 2 Standard yeast + Novamyl113 221 367 10000 BG 3 Yeast expressing 75 160 227 SEQ ID NO: 2, threecassettes 4 Yeast expressing 102 283 403 SEQ ID NO: 1, three cassettes 5Yeast expressing 153 185 190 SEQ ID NO: 3, three cassettes + markers

It can be seen from Table 6 that yeast expressing anti-staling/freshnessenzymes were all better than the control; and the yeast expressing SEQID NO:3 was much better than adding 50 ppm Novamyl 10000 BG at day 7.

1. A recombinant yeast cell comprising a heterologous polynucleotideencoding an anti-staling/freshness amylase.
 2. The recombinant yeastcell according to claim 1, wherein the anti-staling/freshness amylase isselected from the group consisting of a maltogenic amylase (EC3.2.1.133), a beta-amylase (EC 3.2.1.2), and a glucan1,4-alpha-maltotetrahydrolase (EC 3.2.1.60).
 3. The recombinant yeastcell according to claim 1, wherein the heterologous polynucleotideencodes a maltogenic amylase having at least 70% sequence identity toamino acids 20-705 of SEQ ID NO:1.
 4. The recombinant yeast cellaccording to claim 1, wherein the heterologous polynucleotide encodes amaltogenic amylase selected from the group consisting of amino acids20-705 of SEQ ID NO:1, amino acids 20-705 of SEQ ID NO:2, and aminoacids 20-705 of SEQ ID NO:3.
 5. The recombinant yeast cell according toclaim 1, wherein the heterologous polynucleotide encodes a beta-amylasepolypeptide having at least 70% sequence identity to SEQ ID NO:4.
 6. Therecombinant yeast cell according to claim 1, wherein the heterologouspolynucleotide encodes a glucan 1,4-alpha-maltotetrahydrolase having atleast 70% sequence identity to SEQ ID NO:5.
 7. The recombinant yeastcell according to claim 1, wherein the heterologous polynucleotidecomprises a coding sequence having at least 70% sequence identity to SEQID NO: 6, SEQ ID NO:7, or SEQ ID NO:8.
 8. The recombinant yeast cellaccording to claim 1, wherein the cell is a Saccharomyces cell.
 9. Therecombinant yeast cell according to claim 8, wherein the cell is aSaccharomyces cerevisiae cell.
 10. A process for producing a dough,comprising adding the recombinant yeast cell according to claim 1 todough ingredients and making the dough.
 11. The process according toclaim 10, wherein a baked or a steamed product is made from the dough.12. The process according to claim 10, wherein an enzyme selected fromthe group consisting of amylase, glucanase, galactanase, mannanase,aminopeptidase, alpha-amylase, carboxypeptidase, catalase, chitinase,cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, esterase,alpha-galactosidase, beta-galactosidase, glucoamylase,alpha-glucosidase, beta-glucosidase, haloperoxidase, invertase, laccase,lipase, phospholipase, mannosidase, oxidase, pectinolytic enzymes,peptidoglutaminase, peroxidase, phytase, glucose oxidase,polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminaseand xylanase is added to the dough.
 13. The process according to claim1, wherein one of the dough ingredients is flour.
 14. The processaccording to claim 13, wherein the flour is selected from the groupconsisting of wheat, emmer, spelt, einkorn, barley, rye, oat, corn,sorghum, rice, millet, amaranth, quinoa, and cassava and anycombinations thereof.
 15. Use of the recombinant yeast cell according toclaim 1 in dough making.
 16. The recombinant yeast cell according toclaim 1, wherein the recombinant cell is used as a Baker's yeast.